Discharging device of a shaft furnace having cooling means

ABSTRACT

Discharging device of a shaft furnace with the purpose of continuous and even discharge of charged material at high temperature, which material has been reduced in a high temperature atmosphere by means of reducing gas comprising as main components CO and H2 from lumpy iron ore, prepared in advance by pelletizing or granulation having cooling means in which a stationary table is provided at the lower end of the wall of the shaft furnace having a circular form in the horizontal cross-section with an annular clearance being formed between the wall and the stationary table through which the charged materials may pass. A rotary shaft extends through the stationary table which fixedly supports a rotor provided above the stationary table which rotor shape and diameter have a specific relation with the inside diameter of the furnace. Each of the stationary table, the rotor and the shielding wall of the furnace has hollow space formed therein so that it forms a jacket through which cooling fluid can be circulated. An inlet and an outlet pipe are arranged within the rotary shaft for supplying the cooling fluid to the jacket formed in the rotor.

[ Oct. 21, 1975 Primary Examiner-Robert G. Sheridan FURNACE HAVING COOLING MEANS Attorney, Agent, or FirmToren, McGeady and Inventors: Kenjiro Kambara, Sakai; Sakae Stanger Tanaka; Satoru Miyasita, both of Himeji, all of Japan ABSTRACT Nippon Steel Corporation, Tokyo Discharging device of a shaft furnace with the purpose Japan of continuous and even discharge of charged material at high temperature, which material has been reduced p 24, 1974 in a high temperature atmosphere by means of reducing gas comprising as main components CO and H from lumpy iron ore, prepared in advance by pelletizing or granulation having cooling means in which a Foreign Application Prlonty Data stationary table is provided at the lower end of the May 10, 1973 48-51794 wall of the shaft furnace having a circular form in the June 5, 1973 48-66447 horizontal cross-section with an annular clearance being formed between the wall and the stationary 214/18 V table through which the charged materials may pass. C21B 7/14 A rotary shaft extends through the stationary table Field of Search........ 214/18 R, 18 V, 2!, 17 D; which fixedly supports a rotor provided above the sta- 222/409 tionary table which rotor shape and diameter have a specific relation with the inside diameter of the fur- References Cited nace. Each of the stationary table, the rotor and the UNITED STATES PATENTS shielding wall of the furnace has hollow space formed therein so that it forms a jacket through which cooling United States Patent Kambara et al.

[ DISCHARGING DEVICE OF A SHAFT [73] Assignee:

[22] Filed:

[21] Appl. No.: 463,687

[51] Int.

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US. Patent 0a. 21, 1975 3,913,755

FIG.3c FIG.3d

DISCHARGING DEVICE OF A SHAFT FURNACE HAVING COOLING MEANS BACKGROUND OF THE INVENTION:

The present invention relates to a discharging device constituted as a cooling and sheltering construction for discharging continuously and evenly lumpy, pelletized or granulated iron ore having been reduced by means of reducing gas including as main components CO and H in a shaft furnace.

In manufacturing reduced iron by a shaft furnace, iron oxide in the granular or lump form (such as pellets or iron ore in the uniform lump form and the like) has heretofore been charged in the furnace from the upper side thereof and the high temperature atmospheric gas, fuel, air and other gases are introduced into the furnace through the lower side wall or from the bottom thereof so that the charged materials in the granular or lump form are contacted with the high temperature gas in the counterflow thereby effecting the gas reduction operation to the charged materials by the heat treatment thereof, the charged materials in the granular or lump form thus heat treated being cut out and discharged from the furnace by actuating the discharging device provided at the lower portion of the furnace so as to obtain reduced iron of the desired reduction rate.

In case, for example, of obtaining reduced iron by charging iron oxide in the form of granular or lump form from the upper portion of the shaft furnace having inner walls constructed by refractory bricks and introducing high temperature reducing gas having CO.H gas as its main constituent from the lower portion of the furnace so as to contact it with the iron oxide in counterflow thereby effecting the heat treatment thereof for the gas reduction thereof, the reduced iron thus heated to a high temperature is continuously cut out and discharged from the furnace by the rotation of a rotor of the discharging device arranged at the bottom of the shaft furnace.

However, in case when the high-temperature charged materials in the granular or lump form thus heat treated are discharged continuously, it is required for improved quality of the reduced iron to be obtained that the discharging is done in such a manner as to assure uniform descent of the charged materials in the furnace and to minimize the proportion of the materials which is crushed at the discharging device. Also from the point of equipment requirements, when the charged materials in the granular or lump form thus heat treated in the shaft furnace is discharged without being subjected to the cooling process, the heretofore used discharging device is heated to a red hot state under certain circumstances because it contacts with the high temperature atmospheric gas and/or the heat treated charged materials in the granular or lump form held at the high temperature. If the discharging device continues to contact with the heat treated charged materials under the condition described above, the components of the discharging device are extremely worn and the life is shortened.

In order to overcome the above shortages in the aspect of equipments, the components of the device may be constructed by heat-resisting and wear-resisting metals. However, if such metals are used, the cost of the equipment is raised enormously, although the life is prolonged.

This invention aims at avoiding the above described disadvantages tending to occur due to the conventional discharging device and providing a discharging device having cooling means wherein a rotor shape and diameter have a specific relation with the inside diameter of the shaft furnace, and the reduced iron is continuously and uniformly discharged from the horizontal section of the bottom of the shaft furnace so that the shaft furnace can be effectively operated in manufacturing the reduced iron.

SUMMARY OF THE INVENTION:

The object of this invention is, therefore, to provide a novel and useful discharging device of a shaft furnace having cooling means whereby reduced iron having been treated in the furnace can be continuously and evenly discharged from the horizontal section of the bottom of the. furnace while long life of the discharging device is insured.

A first characteristic feature of this invention lies in the fact that the discharging device comprises a stationary table provided at the lower end of the furnace wall of the shaft furnace having circular form in the horizontal section of the bottom thereof with an annular clearance being formed between the lower end of the furnace wall and the stationary table through which the charged materials can be easily passed, a rotor having a shape mainly composed of a curved surface and being located above the stationary table and being supported by a rotary shaft extending through and journaled by the stationary table, the shape of the rotor being of symmetrical form mainly consisting of such curved contour as to give a ratio of its major radius to its minor radius in the range of 1.2 2.0, the atmosphere in contact with the rotor being shielded by the stationary table, the shielding walls and the shut-off valve, the clearance between the rotary shaft and the stationary table being sealed with a sealing member, and the whole being constituted so as not to allow the air direct contact with the lumpy, pelletized or granulated iron ore thus discharged by the rotor.

A second characteristic feature of this invention lies in the fact that each of the above described stationary table, the rotor and the shielding walls constructing the discharging device, each of which directly contacts with the charged materials in the granular or lump form which are to be discharged from the furnace and/or the high temperature atmospheric. gas in the furnace, is formed in a jacket structure through which cooling fluid can be circulated, and the inlet and the outlet pipes for circulating the cooling fluid through the jacket formed in the rotor are located in the rotary shaft.

The first characteristic feature may be embodied either solely or in combination with the second characteristic feature.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view partly in cross-section showing the cooling means of the discharging device in accordance with this invention arranged at the bottom of a shaft furnace for producing reduced iron;

FIG. 2 is a vertical cross-section showing the cooling means incorporated in the rotor and the upper portion of the rotary shaft; and

FIG. 3 (a), 3 (b), 3 (c) and 3 (d) are plan views respectively showing the various contours of the rotor of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Now, preferred embodiments of the discharging device with cooling means incorporated therein constructed in accordance with this invention will be described in detail hereinbelow with reference to the accompanying drawings showing the same.

In the embodiment of this invention shown in FIG. 1, the shaft furnace 1 comprises a furnace wall 3 lined with refractory material 2, and the lower portion of the shaft furnace 1 has a circular form in the horizontal cross-section, A stationary table 4 having a diameter greater than the inner diameter D of the shaft furnace l is arranged at the bottom of the shaft furnace 1. An annular clearance 5 is formed between the stationary table 4 and the lower end of the furnace wall 3 extending circumferentially of the furnace wall 3, the size of the clearance 5 being sufficient to permit the charged materials in the granular or lump form such as reduced iron, for example, to be passed therethrough.

A through-hole is formed at the center of the stationary table 4 through which a rotary shaft 6 extends vertically. A rotor 7 in the form of a flat disc having the thickness greater than the size of the grain or lump of the charged materials is fixedly secured to the upper end of the rotary shaft 6, and the contour of the flat surface of the rotor 7 is of symmetrical form mainly consisting of such curved surface as shown in FIGS. 3a, 3b, 3c and 3d rather than a true circle, wherein the ratio r,/r of the major diameter r to the minor diameter r is in the desired range between 1.2 2.0.

The lower end of the rotary shaft 6 is rotatably supported by a bearing 8 so that the vertical load applied to the rotor 7 is born by the bearing 8 through the rotary shaft 6. Further, the rotary shaft 6 is journaledat its intermediate portion by another bearing 9 secured to the structure 10 so that the horizontal deviation of the shaft 6 is prevented during the rotational movement of the shaft 6. The rotary shaft 6 is coupled with driving means comprised of a motor 11 and a reduction gear 12 through gears 13 and 14. As to the power transmitting mechanism, however, chain and chain wheel mechanism and the like, for example, may be utilized in place of the gears. V

Shielding walls 15, 15A of the discharging device are provided at the clearance 5 between the furnace wall 3 and the stationary table 4, and one or more discharge passage 17 of the charged materials are arranged at the lower end of the annular hollow space 16 surrounded by the shielding walls 15, 15A. Inclined surfaces 15', 15" are formed at the upper portions of the shielding walls 15, 15A which surround the hollow space 16, so that the materials to be charged which have been processed can easily fall into the discharge passage 17. The

shut-off value 18 provided at the lower end of the discharge passage 17 may be in the form of a sluice valve,

tionary table 4 formed therein a hollow space 19 so as to form a jacket structurenFurther, some clearance is formed between the through-hole formed at the center of thestationary table 4 and the rotary shaft 6 extending through the through-hole so as to permit the rotary shaft'6 to be rotated. However, the lower end of the through-hole is sealed by a sealing member 20 so as to prevent the leakage of the gas out of the furnace or the invasion of the exterior air into the furnace. If the sealing member 20 is normally cooled sufficiently by cooling means, its life is prolonged, and the hollow space 19 of the stationary table 4 is extended along the rotary shaft 6 and the lower end of the extension is also sealed by the sealing member 20. An inlet pipe 21 and an outlet pipe 22 for the cooling fluid are connected to the hollow space 19 so that the cooling fluid such as water, for example, is circulated through the hollow space 19.

As shown in FIG. 2, the rotor7 is made in the form of jacket structure in which a hollow space 23 is formed 25 communicates with a supply tube 29 of the cooling fluid through a rotary joint 28.

Now, the cooling effect of the respective components of the discharging device having cooling means therein in accordance with this invention will be described.

When a cooling fluid such as cooling water, for example, is supplied to the supply tubes 29, 25, the cooling water flows out of the opening 27 and spreads over the disc 26 so that the heat of the rotor 7 isabsorbed by the cooling water to lower the temperature thereof and flows downwardly out of the lower'portion of the disc 26 through the annular clearance between the supply pipe 25 and the inner wall of the rotary shaft to be discharged through the through-hole 30 formed at the lower end of the rotary shaft 6. The discharged fluid is led to the exterior of the device by a groove 31.

Each of the shielding walls 15, 15A and the discharge passage 17 surrounded thereby has also formed a hollow space 32, 32' therein so as to form a jacket structure. Supply pipes 33, 33' and discharge pipes 34, 34" for the cooling water are connected to each of the hollow portions 32, 32', respectively, so that the cooling water is circulated through the interior of the shielding walls.

It is often necessary toadjust the degree of cooling depending upon in whichmanner the temperature of the heat treatment of the charged materials in the granular or lump form is to be set or in which way the materials having been processed is to be processed in the succeeding process (i.e., the process after the materials are discharged from the shut-off valve 18). Therefore, heated water, warm water, air and other gases or refrig' erant liquid may be used for cooling fluid in place of the cooling water depending upon the purpose, of the respective processes.

Now, the operation of the discharging deviceconstructed so as to'incorporate the cooling means therein in accordance with this invention will be described.

Since the discharging device of this invention is constructed as described above, the iron oxide in the granular or lump form which is charged in the shaft furnace g and the reduced iron ore supported on the stationary table 4 and the rotor 7, and, under such a condition, the motor 11 is energized so as to drive the rotary shaft 6 at a speed of 0.1 2.0 r p.m., so thatthe reduced iron is continuously pushed'outwardly by the side surface or the peripheral surface of the rotor 7 to thereby forcing the reduced iron to be descended from the periphery of the stationary table 4 and to be passed through the clearance 5. The thus fallen reduced iron is discharged through the discharge passage 17.

In this case, concerning the relationship between the inner diameter D of the shaft furnace 1 and the maximum diameter d of the rotor 7, if the diameter of the rotor 7 is too small, the amount of the discharged material will decrease and, sometimes, it will be made impossible to discharge the materials, thereby increasing the crushing rate of the charged materials in the granular or lump form.

On the other hand, if the diameter of the rotor 7 is too large, the pressure exerted by the charged materials in the furnace will increase thereby requiring a more powerful motor to be provided, while the load applied to the rotary shaft which supports the rotor 7 will increase thereby resulting in disadvantages tending to occur in the type of the discharge device in which the rotary shaft is secured to the center of the rotor as in the case of this invention.

Therefore, as a result of the experiments carried out for obtaining preferred relationship between the inner diameter D of the shaft furnace l and the diameter d of the rotor 7, it has been found to be most effective when the value D/d is selected to be in the range between 1.2 5.0. With respect to the relationship D/d, the value D is determined by the capacity of production of the shaft furnace and the ratio D/a' will be made greater as the value D increase within the above range.

The contour of the rotor 7 having the size satisfying the above mentioned condition and preferably used in the device of this invention is shown in FIGS. 3a, 3b, 3c and 3d, respectively, or the contour of the rotor 7 may include a straight portion. As to the relationship between the maximum radius r and the minimum radius r of the contour of the rotor shown in FIGS. 3a, 3b, 3c and 3d, it has been found that, as the value of r /r approaches 1, the amount of the discharged materials in the granular or lump form will decrease and, when the value r lr is made I, i.e., when the contour of the rotor 7 is made in the circular form, the discharging action is entirely made inoperable.

On the other hand, as the value r /r is made larger, the amount of the discharged materials will increase, but the crushing rate of the discharged materials is also increased approximately in proportion to the increase in the amount of the discharged materials thereby increasing the load applied to the driving means for the rotor.

As a result of the experiments carried out for obtaining preferred relationship between the maximum radius r and the minimum radius r of the rotor 7, it has been found that the charged materials in the granular or lump form can be efficiently discharged when the curved contour or the contour including a straight portion of the rotor 7 is formed by making the value r lr to be within the range of 1.2 2.0.

Therefore, in this invention, a symmetrical rotor 7 having the ratio r /r of the maximum radius r and the minimum radius r of the rotor 7 selected to be within the rangeof 1:2 2.0 is used and the ratio D/d of the inner diameter D of the shaft furnace and the maximum diameterd of the rotor 7 is limited to be within the range of 112 5.0

As described above, by limiting the size of the maximum diameter d of the rotor 7 with respect to the inner diameter D of the shaftfurnace and the ratio of maximum and the. minimum radius r r of the rotor itself to be within the effective ranges, respectively, as described above, the reduced iron is continuously discharged at a constant rate, when the rotational speed of the rotor is held constant, and, as a result of this, the reduced iron supported on the stationary table and the rotor is evenly descended, and a stable gas reduction is carried out in the counter flow of the gas contacting with the charged materials, and yet the crushing rate of the processed materials in the granular or lump form is made to the minimum, while the pressure exerted to the rotor is adjusted to be the minimum at the required rate of discharge of the materials. Further, the wear of the various components of the device and the crushed portion of the granular or lump charged materials are made to the minimum by virtue of the circulation of the cooling fluid during the discharging operation, thereby permitting the discharging operation to be carried out without deteriorating the quality of the product.

In the above description, an embodiment of the discharging device provided in a shaft furnace for producing reduced iron constructed in accordance with this invention has been described. However, it is apparent that, when the discharging device of this invention is applied to a shaft furnace for heat-treating granular or lump form materials having other compositions than those described above, continuous and even discharging operation is equally achieved.

What is claimed is:

1. In a discharging device with cooling means provided in a shaftfurnace the bottom portion of which has a circular shape in horizontal cross-section, said device having a stationary table provided at the lower end of the furnace wall with an annular clearance formed between the lower end of said furnace wall and said stationary table so as to permit the materials charged in said furnace to pass therethrough and a rotor located above said stationary table and supported by a rotary shaft extending through said stationary table, the improvement comprising a first shielding wall extending downwardly from the lower end of said furnace wall past said stationary table, a second shielding wall extending downwardly from the bottom of said stationary table to the same level as the bottom of said first shielding wall, said first and second shielding walls forming a passage therebetween for the discharge of said material, a shut-off valve located at the bottom of said passage to control the rate of discharge of said material from said passage, a sealing member for sealing the clearance between said rotary shaft and said stationary table so that the rotor and the material inside said furnace and passage do not come into direct contact with outside air, and said rotor comprises a symmetrical body having a major and a minor radius, the ratio of the major radius to the minor radius being within the range of 1.2-2.0.

2. Discharging device according to claim 1, wherein said stationary table, said rotor, and said shielding walls comprise a jacket structure having a hollow space therein through which a cooling fluid may be circulated, a supply pipe for introducing the cooling fluid into each of the jacket structures and discharging the same therefrom, said jacket structure for said rotor comprising said supply pipe in said rotary shaft extending therethrough and into said hollow space of said rotOl'.

3. Discharging device according to claim 1, wherein jacket structures of said stationary table and said rotor. 

1. In a discharging device with cooling means provided in a shaft furnace the bottom portion of which has a circular shape in horizontal cross-section, said device having a stationary table provided at the lower end of the furnace wall with an annular clearance formed between the lower end of said furnace wall and said stationary table so as to permit the materials charged in said furnace to pass therethrough and a rotor located above said stationary table and supported by a rotary shaft extending through said stationary table, the improvement comprising a first shielding wall extending downwardly from the lower end of said furnace wall past said stationary table, a second shielding wall extending downwardly from the bottom of said stationary table to the same level as the bottom of said first shielding wall, said first and second shielding walls forming a passage therebetween for the discharge of said material, a shut-off valve located at the bottom of said passage to control the rate of discharge of said material from said passage, a sealing member for sealing the clearance between said rotary shaft and said stationary table so that the rotor and the material inside said furnace and passage do not come into direct contact with outside air, and said rotor comprises a symmetrical body having a major and a minor radius, the ratio of the major radius to the minor radius being within the range of 1.2-2.0.
 2. Discharging device according to claim 1, wherein said stationary table, said rotor, and said shielding walls comprise a jacket structure having a hollow space therein through which a cooling fluid may be circulated, a supply pipe for introducing the cooling fluid into each of the jacket structures and discharging the same therefrom, said jacket structure for said rotor comprising said supply pipe in said rotary shaft extending therethrough and into said hollow space of said rotor.
 3. Discharging device according to claim 1, wherein said rotor is of such size such that the ratio of the inner diameter of the shaft furnace to the major diameter of the rotor is in the range of 1.2 - 5.0.
 4. Discharging device according to claim 2, wherein said sealing member is cooled by at least one of said jacket structures of said stationary table and said rotor. 